Academic literature on the topic 'Maximum curing temperature'

This study aims to investigate the relationship between the heat of hydration and the strength development of cast-in-situ foamed concrete. First, indoor model tests are conducted to determine the effects of the casting density and the fly ash content on the hydration heat of foamed concrete in semiadiabatic conditions. Second, compression tests are carried out to evaluate the development of the compressive strength with the curing time under standard curing conditions and temperature matched curing conditions. Third, the hydration heat development of the foamed concrete is tested in four projects. The results showed that the peak temperature, the maximum temperature change rate, and the maximum temperature difference increased with the increase in the casting density at different positions in the foamed concrete. For the same casting density of the foamed concrete, the peak temperature, the maximum temperature change rate, and the maximum temperature difference decreased with the increase in the fly ash content. For the foamed concrete without the admixture, the early strength was significantly higher under temperature matched curing conditions than under standard curing conditions, but the temperature matched curing conditions had a clear inhibitory effect on the strength of the foamed concrete. The strengths during the early stage and the later stage were both improved under temperature matched curing conditions after adding the fly ash, and the greater the fly ash content, the larger the effect. The maximum temperature increments were higher in the indoor model test than in the field tests for the same casting density. Reasonable cooling measures and the addition of fly ash decreased the maximum temperature increments and increased the corresponding casting times.

The organosilicone gel material for large-power LED packaging was prepared through Si-H addition reaction of hydrogen-silicone with vinyl-silicone catalyzed by Pt coordination compound in this paper. The curing behavior was investigated by DSC method, and the curing dynamic parameters were obtained, i.e., the curing activation energy and reaction level of the system were 79.23kJ/mol and 0.8271 respectively, the initial curing temperature, maximum curing temperature and post-curing temperature were 75°C, 90°Cand 120°C, respectively, which supplied the basic data for the preparation and application of organosilicone materials for large-power LED packaging.

In this study, the bonding reliability of the COG devices was studied. A finite element analyses model was established to study the curing process of COG module. The equivalent stress of the different locations of the package structure and the change of the temperature distribution with time were studied. The heat transfer process and the conductive particle deformation process were displayed through the simulation. The results show that the curing process is the heat transformation and particle deformation process. The residual stress generated by the temperature difference between the curing temperature and the operated temperature. The results show that the maximum residual stress is in the most distorted places of the conductive particles. The maximum residual thermal stress was studied with different bump pitch (35μm 30μm 25μm and 20μm) and the size of the particles (5μm, 4μm and 3.5μm). It shows that for a certain size of the particles, the maximum residual thermal stress will decrease when the bump pitch decreases. For a certain bump pitch, the maximum residual thermal stress will decrease when the size of the particles decrease.

Microwave heating technology is a cost-effective alternative way for heating and curing of used in polymer processing of various alternate materials. The work presented in this paper addresses the attempts made by the authors to study the glass transition temperature and curing of materials such as casting resins R2512, R2515 and laminating resin GPR 2516 in combination with two hardeners ADH 2403 and ADH 2409. The magnetron microwave generator used in this research is operating at a frequency of 2.45 GHz with a hollow rectangular waveguide. During this investigation it has been noted that microwave heated mould materials resulted with higher glass transition temperatures and better microstructure. It also noted that Microwave curing resulted in a shorter curing time to reach the maximum percentage cure. From this study it can be concluded that microwave technology can be efficiently and effectively used to cure new generation alternate polymer materials for manufacture of injection moulds in a rapid and efficient manner. Microwave curing resulted in a shorter curing time to reach the maximum percentage cure.

With the aim to test the applicability of the commonly used maturity concept introduced by Freiesleben et al [1] to modern concrete and to investigate the impact of the curing history on the compressive strength of laboratory samples cured at elevated temperatures, four concretes with different binder compositions (a pure CEM I 42.5N, CEM I 42.5N with fly ash, CEM I 52.5N with fly ash and a CEM III/B) were cured and tested at temperatures ranging from 5 to 60 °C.To test the maturity concept, the development of the compressive strength of samples cured at temperatures ranging from 5 to 60 °C were tested at maturities ranging from 1 to 28 days.To test the impact of curing history at elevated temperatures on the compressive strength, concrete samples were cured at 60°C using two different temperature scenarios: (1) at a constant temperature of 60 °C and (2) at gradually increasing temperature from the casting temperature to the maximum temperature of 60 °C.It was found that the commonly used maturity concept is still applicable to modern concrete although the activation energy is dependent on the binder composition. Concerning the impact of curing history it was found that at 28 days of maturity, the strength of concrete cured at constant temperature of 60 °C was significantly lower than that of concrete cured at 20 °C. For the concrete exposed to gradually increasing temperature up to 60 °C, only a slight decrease in strength was observed for the pure cement concretes while the strength of the binder systems with fly ash increased.

Abstract At digging, peanut (Arachis hypogaea L.) plants were placed in shaded and conventional (inverted) windrows to determine if peanut quality could be improved. Florigiant and NC 6 cultivars were dug and placed in the two windrow types on days when freezing temperatures or frost were predicted. All peanuts were dug with a conventional digger-inverter. The shaded windrows were hand formed by placing a layer of peanuts on the inverted windrow so that the peanuts were protected from direct exposure to the sky. The peanut temperature in the conventional windrow reached the lowest temperature in the nighttime and highest temperature in the daytime and fluctuated from the lowest to highest level compared to the shaded windrow and the ambient temperature. Peanut temperatures in the conventional and shaded windrows were approximately 0C or below for a short duration during the windrow curing period. The average “maximum” peanut temperature from 12 to 5 p.m. was 3.7C higher for the conventional than the shaded windrows for all tests. From 2 to 7 a.m., the average “minimum” peanut temperature was 1.1C lower for the conventional than the shaded windrow. The peanut moisture content in the shaded windrow averaged 7.3% higher at combining than peanuts in the conventional windrow. In a test where the ambient temperature dropped below freezing for two nights following digging, the alcohol headspace meter readings were above the rejection level for freeze damage in the conventional windrow. The shaded windrow provided minimal freeze protection over the conventional windrow and shading is not recommended in the Virginia-Carolina production area.

Curing is the key to the bonding, the study indicate that: curing effect on the glue bond strength, formaldehyde emission as well as Productive Efficiency; the better curing system can ensure the Productive Efficiency in basic to decrease the FE. This paper considered the production practice, studied the curing properties of different MUF resin with TGA. The experimental result: Different curing systems, made different curing process. For A curing system, curing rate is the fastest, the degree of curing is best. Cured stability is well. While in the C curing system, Because of their poor degree of cross-linking, poly-condensation cross-linked imperfect. While, Along with the increasing of n(F):n(U1), initial decomposition temperature increased, the maximum rate of mass loss moved to higher temperature, mass loss declined, decomposition activation energy increases, aging resistance increased.

Abstract The reversion type cure kinetic and induction time models were successfully utilized to predict the isothermal and nonisothermal evolution of the state of cure in vulcanization of the unfilled and carbon black (CB)-filled IR compounds measured by APA 2000. The rate constants for the reversion reaction and the formation of the stable and unstable crosslinks and the parameters of the induction time function with the Arrhenius temperature dependences were determined from the isothermal cure measurements. The equation was proposed to adequately describe the measured dependence of the difference between the maximum and minimum torques as a function of isothermal curing temperature. The measured induction time as a function of heating rate and step temperature variation was successfully predicted based on parameters of the isothermal induction time model. Isothermal cure modeling at each curing temperature individually or at all the curing temperatures simultaneously showed the excellent agreement with the experimental data for both curing and reversion. More severe reversion in the CB-filled IR in comparison with the unfilled IR was explained by comparing their reversion rate constants.

In this article, the curing kinetics of natural rubber (NR) dried by microwave at frequency of 2450MHz was studied using vulcameter, as well as molecular weight. Seen from the results, the molecular weight distribution of NR dried by microwave was wide, the reaction rate of NR dried by microwave at any temperatures increased with conversion degree (α) increment and passed through a maximum at the value ofαbetween 0.1 and 0.3, the peak height ofαwas increased with a shift in peak position towards a higherαvalue, which provided evidences that the curing behavior illustrated autocatalytic characteristics and depended on curing temperature.

Geopolymer has been gradually attracting world attention as a potentially revolutionary material that is one of the ideal substitutes of Portland cement, and fundamental studies on geopolymer are increased rapidly because of its potential commercial applications. However, little work has been done in the field of curing system of geopolymer. In this paper, influence of curing temperature, curing time and curing humidity on the mechanical properties of slag-based geopolymer was studied by using the compressive strength as benchmark parameter. Results have shown that the early age compressive strength of geopolymer increased and the long-term compressive strength decreased at first and then increased as the curing temperature increased, 80°C was the best curing temperature. With prolonging the curing time, it was found that the compressive strength of early age of geopolymer reached the maximum ( 116.3 MPa for 1d, 97.5 MPa for 3d) as the curing time was 12h, and that of 28d geopolymer was 91.3 MPa as the curing time was 10h. It was also found that the compressive strength of geopolymer reduced evidently as the humidity increased.

Submitted by Erika Demachki (erikademachki@gmail.com) on 2014-10-23T17:14:40Z No. of bitstreams: 2 Dissertação - Mário Henrique Gomes Brito - 2013.pdf: 6257761 bytes, checksum: 3ff568c727b44a8a7e645c8475216a03 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5)<br>Approved for entry into archive by Jaqueline Silva (jtas29@gmail.com) on 2014-10-23T18:50:27Z (GMT) No. of bitstreams: 2 Dissertação - Mário Henrique Gomes Brito - 2013.pdf: 6257761 bytes, checksum: 3ff568c727b44a8a7e645c8475216a03 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5)<br>Made available in DSpace on 2014-10-23T18:50:27Z (GMT). No. of bitstreams: 2 Dissertação - Mário Henrique Gomes Brito - 2013.pdf: 6257761 bytes, checksum: 3ff568c727b44a8a7e645c8475216a03 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2013-04-30<br>Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES<br>The overall objective of this research, which was essentially experimental, is to study the influence of the isothermal period and the maximum temperature of the thermal cure cycle steam under atmospheric pressure in the development of compressive strength of concrete blocks over time. The influences of two other types of curing are also being investigated; curing by enveloping with plastic sheet and open air curing, considered the last case scenario for reference. This study specifically aimed to further our understanding on how to; a) evaluate and quantify the importance of adopting procedures for curing the average resistance (Fbm) and characteristic (fbk) strength to compression of concrete blocks, comparing the processes of thermal curing and curing by enveloping plastic sheet to open air curing; b) evaluate statistically the aging effect of blocks over its compressive strength; c) evaluate the interaction effects of the variables "type of cure" and "age analysis" of the results of compressive strength of concrete blocks; and d) identify the main changes in the microstructure of the blocks subjected to a thermal curing process, especially observing eventual delayed ettringite formation in the internal structure of the material. To examine the influence of maximum curing temperature, two levels were adopted; 65°C and 85°C. As for analyzing the influence of isothermal period, three levels were adopted; 3 hours, 4 hours and 5 hours. The age analysis was evaluated in five levels; 1, 3, 7, 28 and 91 days. The results showed that the worst condition for curing, or curing type, was the open air curing (curing time approximately equal to 24 hours), which led to a lower overall average result of compressive strength of concrete blocks, proving the importance of adopting procedures of curing to optimize the mechanical performance of concrete blocks. Furthermore, it was also determined that the best curing conditions were the curing with enveloping plastic sheet (curing time approximately equal to 24 hours) and the thermal curing with steam under atmospheric pressure isotherm of 65°C and isothermal period of 3 hours (curing time approximately equals 8.5 hours), which were considered statistically equal. It was also observed that there was no significant influence of the curing in maximum temperature in relation to the compressive strength of the blocks. In the other hand, the isothermal period was very significant; the best condition was 3 hours, while 4 hours and 5 hours were considered statistically equal. Regarding the delayed ettringite formation, it was only verified for thermal curing conditions of isothermal of 85°C and isothermal period of 4 hours and 5 hours.<br>O objetivo geral desta pesquisa, de caráter essencialmente experimental, é estudar a influência do período isotérmico e da temperatura máxima do ciclo de cura térmica a vapor sob pressão atmosférica no desenvolvimento da resistência à compressão de blocos de concreto ao longo do tempo. Paralelamente, foram investigadas ainda as influências de dois outros tipos de cura, a saber: cura por envelopamento com lona plástica e cura ao ar livre, considerada esta última a situação de referência. De modo específico, o estudo visou ainda: a) avaliar e quantificar a importância da adoção de procedimentos de cura nas resistências média (fbm) e característica (fbk) à compressão de blocos de concreto, comparando os processos de cura térmica e cura por envelopamento com lona plástica com a cura ao ar livre; b) avaliar estatisticamente o efeito da idade dos blocos sobre a sua resistência à compressão; c) avaliar a interação dos efeitos das variáveis “tipo de cura” e “idade de análise” sobre os resultados de resistência à compressão dos blocos de concreto; e d) identificar as principais transformações ocorridas na microestrutura dos blocos submetidos aos processos de cura térmica, em especial observando eventual formação de etringita tardia na estrutura interna do material. Para analisar a influência da temperatura máxima de cura, foram adotados dois níveis: 65°C e 85°C. Já para analisar a influência do período isotérmico, foram adotados três níveis: 3 horas, 4 horas e 5 horas. Por sua vez, a idade de análise foi avaliada em cinco níveis: 1, 3, 7, 28 e 91 dias. Os resultados mostraram que a pior condição de cura, ou seja, o tipo de cura que conduziu ao menor resultado médio global de resistência à compressão dos blocos de concreto, foi a cura ao ar livre (tempo de cura aproximadamente igual a 24 horas), comprovando a importância da adoção de procedimentos de cura para a otimização do desempenho mecânico dos blocos de concreto. Além disso, foi verificado ainda que as melhores condições de cura foram a cura por envelopamento com lona plástica (tempo de cura aproximadamente igual a 24 horas) e a cura térmica a vapor sob pressão atmosférica com isoterma de 65°C e período isotérmico de 3 horas (tempo de cura aproximadamente igual a 8,5 horas), os quais foram considerados, estatisticamente, iguais. Também foi verificado que não houve influência significativa da temperatura máxima de cura em relação à resistência à compressão dos blocos. Já o período isotérmico foi significativo, de modo que a melhor condição foi 3 horas, enquanto 4 horas e 5 horas foram considerados, estatisticamente, iguais. Quanto à formação de etringita tardia, esta só foi verificada para as condições de cura térmica com isoterma de 85°C e períodos isotérmicos de 4 horas e 5 horas.

Fibre Reinforced Polymers (FRP) have been widely applied in various industries due to their outstanding properties. As a promising curing technology for FRP parts, the self-resistance electric (SRE) heating method has attracted plenty of attention. However, it is difficult for the SRE heating method to uniformly cure the FRP parts with irregular structures. In this paper, a multi-zoned SRE heating method is proposed, in which the FRP part is divided into several heating zones and the temperature of each zone is regulated independently. A multi-channel electrical voltage control system is developed to realise the multi-zoned SRE heating of a wing-shaped FRP part, in which a rapid zone-based temperature control responsiveness is achieved, and the maximum temperature difference is reduced from 60 °C to less than 10 °C, reaching 2.5 °C at its best. This work presents an alternative for the high efficiency and energy-saving curing process of FRP parts.

This chapter explains the effect of compositional modification on the magnetoelectric coefficient in sintered piezoelectric – magnetostrictive composites. It was found that 15 at% doping of Pb(Zn1/3Nb2/3)O3 [PZN] in Pb(Zr0.52Ti0.48)O3 [PZT] enhances the piezoelectric and magnetoelectric properties of a PZT – 20 at% Ni0.8Zn0.2Fe2O4 [NZF] composite. The effect of doping on the ferromagnetic phase was also investigated. With increases in Zn concentration, it was found that the coercive field and Curie temperature of Ni(1-x)ZnxFe2O4 [NZF] decreases, while its saturation magnetization has a maxima at 30 mole% Zn. X-ray diffraction revealed that the lattice constant of NZF increases from 8.32 Å for 0 at% Zn to 8.39 Å for 50 at% Zn. The magnetoelectric coefficient was found to have a maxima of 144 mV/cm.Oe at 30 at% Zn. To understand better, the effect of 40% (by mole) Zn substitution on structural, piezoelectric, ferromagnetic and magnetoelectric properties of Pb(Zr0.52Ti0.48)O3 - CoFe2O4 (PZT - CFO) sintered composite is also explained. X-ray diffraction of Co0.6Zn0.4Fe2O4 (CZF) showed the shift in almost all diffraction peaks to lower diffraction angle confirming the increase in lattice parameter in all three direction from 8.378 (for CFO) to 8.395 Å for (Co,Zn)Fe2O4 (CZF). SEM and TEM results showed defect structure (cleavage, twins, strain fields) in the CZF particle, which is a clear indication of misfit strain developed due to lattice expansion. Magnetic properties measured over temperature (5 K – 1000 K) showed increased magnetization but lower magnetic Curie temperature in PZT - CZF particle. Magnetoelectric coefficient measured as function of ferrite concentration showed an increase of more than 100% after doping the CFO phase with 40% Zn. This enhancement can be attributed to increase in the lattice strain, magnetic permeability and decrease in coercivity.

Many current bone cements have proprietary minor ingredients that affect the chemical kinetics and heat transfer modeling of the exothermic reaction during bone cement polymerization. In addition, the geometry and the method of cooling/curing the bone cement can vary by application. A method for modeling energy generation, based on temperature measurement of various geometries and conditions, expresses the exothermic reaction and the duration with respect to time. Reaction from the bone cement can yield temperatures above 110°C for the air convective cooling boundary condition. Experiments show that by using cold irrigation cooling (saline) with an initial temperature of 1.5°C, the maximum reaction temperature of the PMMA cement approaches 40°C depending upon the thickness of the cement. For bone cement cooled in air and saline at room temperature, the exothermic reaction begins around 400 seconds (8 min) after the compounds are mixed. When cold saline is applied, the time-delay of the reaction is approximately 300 additional seconds compared to the two room temperature cases. Finally, based on compression testing, the structural behavior of the PMMA cement is improved when the material is cured in a slower and wet environment.

We have developed a simple, low cost technique using new materials to bond capacitance pressure sensors. The old methods have difficult processes when a metal trace on the bonding area perturbs the sealing. The new method uses a polymeric gap-controlling block between glass and silicon wafers and a heat curing adhesive which penetrates between them due to capillary force. We used two different materials including SU-8™ and UV (ultraviolet) curing adhesive in order to control the gap. The technique allows us to generate a small gap between the chips due to low viscosity of the heat curing adhesive, align and bond chips immediately, make a strong bond, and easily seal the sensor. Also, the high temperature, strong heat curing adhesive makes the sensor suitable for high temperature and high pressure applications. The sensors were tested up to 2 MPa and 170°C in a nitrogen chamber. The maximum thermal error of ±1.74% and ±1% full scale output (FSO) were measured for SU-8 and UV sensors, respectively.

The bonding strength of metal-to-metal lap joining of a two-part epoxy-based adhesive employed in an automotive assembly line was investigated under different heating rates (10°C/min to 6000°C/min), peak temperatures (room to 250°C), and holding times. The results indicate that bonding strength is mainly controlled by the peak curing temperature and the heating rate. The maximum bonding strength appears between 70–110°C, but the value of it depends on the heating rate. At heating rates of 10°C/min, 50°C/min, and 100°C/min the peak strength decreases with increasing heating rate. However, further increase in heating rate to 2000–6000°C/min resulted in higher peak bonding strength. The microstructures and fractured surfaces after shear testing were examined by a scanning electron microscope (SEM). The results revealed that many gas bubbles (voids) were formed during the adhesive curing process, and the fracture process was controlled by the link of the voids. At low heating rates (10–100°C/min) the mean void size and volume fraction increase with heating rate and peak temperature, causing the weakening to the bonding strength. But at very high heating rates (2000–6000°C/min) the rapid hardening of the adhesive suppressed the development of gas bubbles, so the mean void size and volume fraction were low, and the bonding strength was high. This result indicates that to effectively improve the adhesive bonding strength, both the chemical reaction (degree of cure) and physical response (gas bubble formation) need to be optimized.

The effect of nanoclay on the cure kinetics of glass/waterborne epoxy nanocomposites is investigated. First step in sample preparation involves dispersing Cloisite® Na+, a natural montmorillonite, in distilled water at 70°C with the aid of a sonicator. Then, desired amounts of dicyandiamide and 2-methyl imidazole, serving as cross-linkers, are mixed to the aqueous nanoclay solution. As the mixing continues, Epi-Rez 3522-W-60 waterborne epoxy resin is introduced to the solution and the compound is mixed for an additional 30 minutes. The nanoclay content of this batch is adjusted to be at 2wt%. An identical second batch, which does not comprise nanoclay, is also prepared to serve as the baseline data. Glass/waterborne epoxy prepregs containing 30% glass fibers are prepared from these batches and used to characterize the effects of nanoclay. The evolution of viscoelastic properties during curing are characterized by the APA2000 rheometer. Using the storage and loss moduli profiles during curing, gel time and maximum storage modulus are characterized. Effect of nanoclay on the glass transition temperature is determined by applying an additional temperature cycle following the cure cycle. In addition, mechanical performances of the samples are characterized by three point bending tests. Nanoclay is observed to yield 2-fold higher storage modulus during curing. Rate of curing is measured to be substantially slower for the samples comprising nanoclay. In addition, glass transition temperature improved by 5% to 99°C with the addition of nanoclay compared to 94.5°C for the samples without nanoclay. Flexural stiffness of the samples containing nanoclay is measured to be 20% higher than the samples without nanoclay while the strength remained virtually unaffected.

An experimental study has been performed in order to determine the thermal characteristics of a specific concrete formula to be used for a large-scale tank-grouting project. The experimental results were incorporated into finite-element numerical simulations aimed at predicting local concrete temperatures over the duration of multiple concrete pours. The pours will occur in a stepwise fashion whereby each additional concrete layer will be added while the previous layers are still undergoing the curing process. The experimental portion of the project included a series of laboratory-scale tests aimed at determining the time-dependent adiabatic temperature rise of several concrete samples and the corresponding time-dependent concrete internal heating rates. Results of the experiments were incorporated directly into the finite-element thermal model. The finite-element simulations indicated that the pour schedule did not have a strong influence on the maximum temperature in the concrete.

Abstract Flexible and sensitive strain sensors can be utilized as wearable sensors and electronic devices in a wide range of applications, such as personal health monitoring, sports performance, and electronic skin. This paper presents the fabrication of a highly flexible and sensitive strain sensor by 3D printing an electrically conductive polydimethylsiloxane (PDMS)/multi-wall carbon nanotube (MWNT) nanocomposite on a PDMS substrate. To maximize the sensor’s gauge factor, the effects of MWNT concentration on the strain sensing function in nanocomposites are evaluated. Critical 3D printing and curing parameters, such as 3D printing nozzle diameter and nanocomposites curing temperature, are explored to achieve the highest piezoresistive response, showing that utilizing a smaller deposition nozzle size and higher curing temperature can result in a higher gauge factor. The optimized 3D printed nanocomposite sensor’s sensitivity is characterized under cyclic tensile loads at different maximum strains and loading rates. A linear piezoresistive response is observed up to 70% strain with an average gauge factor of 12, pointing to the sensor’s potential as a flexible strain sensor. In addition, the sensing function is almost independent of the applied load rate. The fabricated sensors are attached to a glove and used as a wearable sensor by detecting human finger and wrist motion. The results indicate that this 3D printed functional nanocomposite shows promise in a broad range of applications, including wearable and skin mounted sensors.

Abstract The rate of one-year mortality after osteoporotic hip fracture in elderly is reported to be more than 20%. Hip augmentation using polymethylmethacrylate (PMMA) is an alternative preventive approach for patients at the highest risk of osteoporotic fracture. Excessive injection volumes of PMMA however may introduce the risk of thermal osteonecrosis. We have previously proposed a Finite element (FE) simulation to estimate the bone temperature elevations after cement injection in three key locations and demonstrated an agreement between the simulation results and the temperature measurements during the experiment. Previous study showed that the maximum temperature-rise measured at the hip surface is 10°C. The aim of this study is to introduce a cooling approach to reduce the PMMA’s curing temperature after cement injection during hip augmentation. For this purpose, we perform a conductive cooling experiment with a metallic K-wire attached to an ice-water bath. We also create a finite element simulation model for the proposed cooling system to estimate the peak temperature reduction and compare the simulation results with experimental data. Simulation results demonstrate the decrease of 80% of peak curing temperature during PMMA polymerization; similarly, sawbone experiments also show that on average the peak temperature has been reduced 64% when cooling system is integrated to the hip augmentation procedure.

The dominating parameter for heat transfer during continuous curing of extruded high voltage cables is the thermal conductivity of molten polyethylene. Literature on thermal conductivity has been reviewed, and it is found that there are differences of order 50% between different investigations. From numerical simulations it is found that 20% increase in thermal conductivity corresponds to 8 °C increase in maximum conductor temperature for constant line speed or 16% increase in line speed for optimized crosslinking. The calculated conductor temperature profile is compared with experimental data from the cable manufacturing. The conductor temperature was measured continuously, using an optical fiber embedded in the outer layer of the conductor, while the conductor passed through the extrusion line. The comparison between measured and simulated conductor temperature profiles show good agreement provided that an appropriate value of the thermal conductivity is chosen.

A systematic study has been conducted on processing and characterizing of carbon fiber reinforced epoxy polymer (CFRP) composites to enhance their properties through the optimization of graphene nanoplatelet (GNP). GNP having a two dimensional structure is composed of several layers of graphite nanocrystals stacked together. GNP is expected to provide better reinforcing effect in polymer matrix composites as a nanofiller along with greatly improved mechanical and thermal properties due to its planar structure and ultrahigh aspect ratio. GNP is also considered to be the novel nanofiller due to its exceptional functionalities, high mechanical strength, chemical stability, abundance in nature, and cost effectiveness. Moreover, it possesses an extremely high-specific surface area which carries a high level of transferring stress across the interface and provides higher reinforcement than carbon nanotubes (CNT) in polymer composites. Hence, this extensive research has been focused on the reinforcing effect of amino-functionalized GNP on mechanical properties of carbon fiber reinforced epoxy composites. Amine functionalized GNP was integrated in EPON 828 at different loadings, including 0.1, 0.2, 0.3, 0.4, and 0.5 wt%, as a reinforcing agent. GNP was infused into Epon 828 resin using a high intensity ultrasonic processor followed by a three roll milling for better dispersion. Epikure 3223 curing agent was then added to the modified resin and mixed using a high-speed mechanical stirrer. The mixture was then placed in a vacuum oven at 40 °C for 10 min to ensure the complete removal of entrapped bubbles and thus reduce the chance of void formation. Finally, both conventional and nanophased carbon fiber reinforced epoxy polymer (CFRP) composites were fabricated by employing a combination of hand lay-up and compression hot press techniques. Carbon woven fabrics were properly stacked into eleven layers while maintaining their parallel orientation. Modified epoxy resin was smeared uniformly on each fabric layer using a brush and a wooden roller. The fabric stack was then wrapped with a bleeder cloth and a nonporous Teflon cloth and placed on the plates of the hot press where pressure and temperature were controlled precisely to ascertain maximum wetting of fibers with matrix and compaction of the layup as well as curing. Temperature was kept at 60 °C for 1 hour to attain enough flow of resin at lower viscosity as compared to room temperature and at the same time not to let it flow out of the layup. Temperature was then increased to 100 °C and maintained for 1 hour to obtain completely cured carbon-epoxy composites. After completion of the curing cycles, the laminate was allowed to cool down slowly to avoid any unwanted shrinkage. The conventional CFRP composite were fabricated in a similar fashion. Mechanical properties were determined through flexure and tensile tests according to ASTM standards. In all cases, 0.4 wt% GNP infused epoxy nanocomposite exhibited the best properties. The 0.4 wt% GNP modified carbon fiber/epoxy composites exhibited 19% improvement in the flexure strength and 15% improvement in the flexure modulus. Tensile test results of CFRP composites showed a maximum improvement in the tensile strength and tensile modulus by about 18% and 19%, respectively, for the 0.4 wt% GNP-infused samples over the control sample. Both flexural and tensile properties were observed to reach the highest at the 0.4 wt% loading due to the better interfacial interaction and effective load transfer between the NH2-GNP and the epoxy resin. Furthermore, morphological analysis ensured better dispersion and improved interfacial adhesion between the matrix and the fiber for GNP reinforced composites.

A curing press is used in the final phase of tire manufacture. A tire semi product is placed into the curing press mold and a specific pressure and temperature gives it its final shape and final mechanical properties. There are many types of curing presses; this particular press is mechanical and the pressing force is exerted by an eccentric mechanism. The size of this press allows production of tires for trucks and medium-sized tractors. The basic demands placed on this type of press include tightness of the parts which are exposed to pressure from the heating medium. This paper mainly focuses on the tightness of the vulcanizing chamber and the tightness of the mold in which the semi product of the tire is inserted. Leakage of the vulcanizing chamber may cause leakage of the heating medium which could result in injury to the machine operator. Leakage of the mold causes an overflow of rubber into the parting plane, which may result in the production of rejects. To ensure the tightness of both these components, it is necessary to create sufficient pressure between the individual components. The value of the compressive force depends on the setting of the overlap of these parts, which depends on the stiffness of the individual parts and on the force exerted from the pressure of the heating medium that acts on these parts. Finite element method (FEM) analysis of this problem was performed using Abaqus software. A computational model of the curing press was created for this numerical analysis. The geometry of the press is symmetrical and the load is centric, therefore, only half of the press was modelled. The aim of this analysis was to find the most suitable settings for the overlap of the mold (independent variable) and the overlap of the chamber (dependent variable) which ensure the smallest possible leakage of the mold and an uninterrupted contact surface between the sealing and the upper part of the chamber. The sealing of the chamber is made from rubber which was modelled for the analysis as a five term generalized Mooney-Rivlin model, also known as the James-Green-Simpson model. This model assumes hyperelastic behavior with incompressibility. The insulating plates are made of a particulate composite which was considered to be linear with isotropic properties. For strength evaluation of the composite materials, all individual components of the stress tensor were investigated according to the maximum stress criterion. Hook’s law was considered to be valid for all the metallic materials. The Von Mises criterion was used to evaluate the strength of the metallic materials. The geometry of the press was discretized using 3D linear elements with 8 nodes and with reduced integration (C3D8R). The geometry of the rubber sealing was discretized using hybrid 3D linear elements with 8 nodes and with reduced integration (C3D8RH). The overall number of elements was approximately 97,000. Calculation model enabled to compute the best overlap setting of the chamber and the mold. This setting ensures their tightness. Effect of the setting to a stress in a press was also studied and the values of the stress were in a permitted range.